Linear Technology LTC1278-4ISW, LTC1278-4IN, LTC1278-4CSW, LTC1278-4CN, LTC1278-5CN Datasheet

LTC1278

INPUT FREQUENCY (Hz)

10k

0

EFFECTIVE NUMBER OF BITS

S/(N+D) (dB)

3

5

7

10

100k 1M 2M

LT1278 G4

1

4

6

9

12
11

62
56

74
68

8

2

f

SAMPLE

= 500kHz

NYQUIST

FREQUENCY

12-Bit, 500ksps Sampling

A/D Converter with Shutdown

EATU

F

■

Single Supply 5V or ±5V Operation

■

Two Speed Grades,500ksps (LTC1278-5)

RE

S

400ksps (LTC1278-4)

■

70dB S/(N + D) and 74dB THD at Nyquist

■

No Missing Codes Over Temperature

■

75mW (Typ) Power Dissipation

■

Power Shutdown with Instant Wake-Up

■

Internal Reference Can Be Overdriven Externally

■

Internal Synchronized Clock; No Clock Required

■

High Impedance Analog Input

■

0V to 5V or ±2.5V Input Range

■

New Flexible, Friendly Parallel Interface to DSPs
and FIFOs

■

24-Pin Narrow PDIP and SW Packages

U

O

PPLICATI

A

■

High Speed Data Acquisition

■

Digital Signal Processing

■

Multiplexed Data Acquisition Systems

■

Audio and Telecom Processing

■

Spectrum Analysis

, LTC and LT are registered trademarks of Linear Technology Corporation.

S

DUESCRIPTIO

The LTC®1278 is a 1.6µ s, 500ksps, sampling 12-bit A/D
converter that draws only 75mW from a single 5V or ±5V
supplies. This easy-to-use device comes complete with
a 200ns sample-and-hold, a precision reference and an
internally trimmed clock. Unipolar and bipolar conver­sion modes add to the flexibility of the ADC. The low
power dissipation is made even more attractive by a

8.5mW power-down feature. Instant wake-up from shut­down allows the converter to be powered down even
during brief inactive periods.

The LTC1278 converts 0V to 5V unipolar inputs from a
single 5V supply and ±2.5V bipolar inputs from ±5V
supplies. Maximum DC specs include ±1LSB INL and
±1LSB DNL. Outstanding guaranteed AC performance
includes 70dB S/(N + D) and 78dB THD at the input
frequency of 100kHz over temperature.

The internal clock is trimmed for 1.6µs conversion time.
The clock automatically synchronizes to each sample
command, eliminating problems with asynchronous clock
noise found in competitive devices. A separate convert
start input and a data ready signal (BUSY) ease connec­tions to FIFOs, DSPs and microprocessors.

Single 5V Supply, 500kHz, 12-Bit Sampling A/D Converter

2.42V

REFERENCE

OUTPUT

10µF

A

PPLICATITYPICAL

+

ANALOG INPUT

(0V TO 5V)

0.1µF

12-BIT

PARALLEL

BUS

10
11
12

1

AIN

2

V

3

AGND

4

D11(MSB)

5

D10

6

D9

7

D8

8

D7

9

D6
D5
D4
DGND

O

LTC1278-5



REF

CONVST

U

AV

BUSY

SHDN

DV

Effective Bits and Signal-to-(Noise + Distortion)

24



DD

23

V



RD

SS

CS



DD

D0
D1
D2
D3

10µF

22
21

µP CONTROL

20

LINES

19

CONVERSION START INPUT

18

POWER DOWN INPUT

17
16
15
14
13

LTC1278 • TA01

5V

+

0.1µF

vs Input Frequency

1

LTC1278

WU

U

PACKAGE

/

O

RDER I FOR ATIO

W

O

A

AVDD = DVDD = VDD (Notes 1, 2)

LUTEXI T

S

A

WUW

ARB

U
G

I

S

Supply Voltage (VDD).............................................. 12V

Negative Supply Voltage (VSS)

Bipolar Operation Only .......................... – 6V to GND

Total Supply Voltage (VDD to VSS)

Bipolar Operation Only ....................................... 12V

Analog Input Voltage (Note 3)

Unipolar Operation ................... – 0.3V to VDD + 0.3V

Bipolar Operation............... VSS – 0.3V to VDD + 0.3V

Digital Input Voltage (Note 4)

Unipolar Operation ................................–0.3V to 12V

Bipolar Operation........................... VSS – 0.3V to 12V

Digital Output Voltage

Unipolar Operation ................... –0.3V to VDD + 0.3V

Bipolar Operation................ VSS – 0.3V to VDD + 0.3V

Power Dissipation............................................. 500mW

Operating Temperature Range

LTC1278-4C, LTC1278-5C ..................... 0°C to 70°C

LTC1278-4I ....................................... –40°C to 85°C

Storage Temperature Range ................ –65°C to 150°C

Lead Temperature (Soldering, 10 sec)................. 300°C

TOP VIEW

A



1

IN

V



2

REF

AGND

3

D11 (MSB)

Consult factory for Military grade parts.

4

D10

5

D9

6

D8

7

D7

8

D6

9

D5

10

D4

11

DGND

12

N PACKAGE

24-LEAD PDIP

T

= 110°C, θJA = 100°C/W (N)

JMAX

T

= 110°C, θJA = 130°C/W (SW)

JMAX

24-LEAD PLASTIC SO WIDE

AVDD

24

V

23

SS

BUSY

22

CS

21

RD

20

CONVST

19

SHDN

18

DV

17

D0

16

D1

15

D2

14

D3

13

SW PACKAGE



DD

ORDER

PART NUMBER

LTC1278-4CN
LTC1278-5CN
LTC1278-4IN
LTC1278-4CSW



LTC1278-5CSW
LTC1278-4ISW

U

With Internal Reference (Notes 5, 6)

LTC1278-4/LTC1278-5

● ±6 LSB

LTC1278-4/LTC1278-5

U

IN

IN

VERTER

CCHARA TERIST

= 0 ● ±10 ±45 ppm/°C

OUT(REF)

ICS

U
PUT

LOG

Analog Input Range (Note 9) 4.95V ≤ VDD ≤ 5.25V (Unipolar) ● 0 to 5 V

Analog Input Leakage Current CS = High ● ±1 µA
Analog Input Capacitance Between Conversions (Sample Mode) 45 pF

IA

(Note 5)

4.75V ≤ VDD ≤ 5.25V, –5.25V ≤ VSS ≤ – 2.45V (Bipolar) ● ±2.5 V

During Conversions (Hold Mode) 5 pF

CO

PARAMETER CONDITIONS MIN TYP MAX UNITS

Resolution (No Missing Codes) ● 12 Bit
Integral Linearity Error (Note 7) ● ±1 LSB
Differential Linearity Error ● ±1 LSB
Offset Error (Note 8) ±4 LSB

Gain Error ±15 LSB
Gain Error Tempco I

A

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

I

IN

C

2

LTC1278

W

U

IC

DY

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

S/(N + D) Signal-to-Noise Plus Distortion Ratio 100kHz Input Signal ● 70 72 dB

THD Total Harmonic Distortion 100kHz Input Signal ● –80 –78 dB

IMD Intermodulation Distortion f

A

ACCURACY

First 5 Harmonics 250kHz Input Signal –74 dB
Peak Harmonic or Spurious Noise 100kHz Input Signal ● –84 –78 dB

Full Power Bandwidth 4 MHz
Full Linear Bandwidth (S/(N + D) ≥ 68dB) 350 kHz

(Note 5)

LTC1278-4/LTC1278-5

250kHz Input Signal 70 dB

250kHz Input Signal –74 dB

= 99.37kHz, f

IN1

= 249.37kHz, f

f

IN1

= 102.4kHz –82 dB

IN2

= 252.4kHz –70 dB

IN2

U

I TER AL REFERE CE CHARACTERISTICS

PARAMETER CONDITIONS MIN TYP MAX UNITS

V

REF

V

REF

V

REF

V

REF

DIGITAL I PUTS A D DIGITAL OUTPUTS

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IH

V

IL

I

IN

C

IN

V

OH

V

OL

I

OZ

C

OZ

I

SOURCE

I

SINK

UU

(Note 5)

LTC1278-4/LTC1278-5

Output Voltage I
Output Tempco I
Line Regulation 4.95V ≤ VDD ≤ 5.25V 0.01 LSB/V

Load Regulation 0V ≤ |I

U

High Level Input Voltage V
Low Level Input Voltage VDD = 4.95V ● 0.8 V
Digital Input Current VIN = 0V to V
Digital Input Capacitance 5pF
High Level Output Voltage VDD = 4.95V

Low Level Output Voltage VDD = 4.95V

High Z Output Leakage D11 to D0 V
High Z Output Capacitance D11 to D0 CS High (Note 9 ) ● 15 pF
Output Source Current V
Output Sink Current V

= 0 2.400 2.420 2.440 V

OUT

= 0 ● ±10 ±45 ppm/°C

OUT

–5.25V ≤ V

≤ –4.95V 0.01 LSB/V

SS

| ≤ 1mA 2 LSB/mA

OUT

U

(Note 5)

LTC1278-4/LTC1278-5

= 5.25V ● 2.4 V

DD

DD

IO = –10µA 4.7 V
IO = –200µA ● 4V

IO = 160µA 0.05 V
IO = 1.6mA ● 0.10 0.4 V

= 0V to VDD, CS High ● ±10 µA

OUT

= 0V –10 mA

OUT

= V

OUT

DD

● ±10 µA

10 mA

3

LTC1278

U

W

POWER REQUIRE E TS

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

DD

V

SS

I

DD

I

SS

P

D

Positive Supply Voltage (Notes 10, 11) Unipolar 4.95 5.25 V

Negative Supply Voltage (Note 10) Bipolar Only –2.45 –5.25 V
Positive Supply Current f

Negative Supply Current f
Power Dissipation f

W

U

TI I G CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

f

SAMPLE(MAX)

t

SAMPLE(MIN)

t

CONV

t

ACQ

t

1

t

2

t

3

t

4

t

5

t

6

t

7

t

8

t

9

t

10

t

11

t

12

Maximum Sampling Frequency LTC1278-4 ● 400 kHz

Minimum Throughput Time LTC1278-4 ● 2.5 µs
(Acquisition Time Plus Conversion Time) LTC1278-5 ● 2.0 µs

Conversion Time LTC1278-4 2.0 2.3 µs

Acquisition Time 200 ns
CS↓ to RD↓ Setup Time (Notes 9, 10) ● 0ns
CS↓ to CONVST↓ Setup Time (Notes 9, 10) ● 20 ns
SHDN↑ to CONVST↓ Wake-Up Time (Note 10) 350 ns
CONVST Low Time (Notes 10, 12) ● 40 ns
CONVST↓ to BUSY↓ Delay CL = 100pF 40 110 ns

Data Ready Before BUSY↑ CL = 100pF ● 20 40 ns
Wait Time RD↓ After BUSY↑ Mode 2, (see Figure 14) (Note 9) ● –20 ns
Data Access Time After RD↓ CL = 20pF (Note 9) 50 90 ns

Bus Relinquish Time 20 30 75 ns

RD Low Time (Note 9) ● t
CONVST High Time (Notes 9, 12) ● 40 ns
Aperture Delay of Sample-and-Hold Jitter <50ps 15 ns

(Note 5)

LTC1278-4/LTC1278-5

Bipolar 4.75 5.25 V

= 500ksps ● 15.0 29.5 mA

SAMPLE

SHDN = 0V ● 1.7 3.0 mA

= 500ksps, VSS = –5V ● 0.12 0.30 mA

SAMPLE

= 500ksps ● 75.0 150 mW

SAMPLE

SHDN = 0V ● 8.5 15 mW

(Note 5)

LTC1278-4/LTC1278-5

LTC1278-5 ● 500

LTC1278-5 1.6 1.85 µs

Commercial
Industrial ● 140 ns

Commercial
Industrial ● 120 ns

CL = 100pF 70 125 ns
Commercial
Industrial ● 170 ns

Commercial
Industrial ● 20 90 ns

● 130 ns

● 110 ns

● 150 ns

● 20 85 ns

8

ns

4

W

INPUT FREQUENCY (Hz)

10k

0

EFFECTIVE NUMBER OF BITS

S/(N+D) (dB)

3

5

7

10

100k 1M 2M

LT1278 G4

1

4

6

9

12
11

62
56

74
68

8

2

f

SAMPLE

= 500kHz

NYQUIST

FREQUENCY

U

TI I G CHARACTERISTICS

LTC1278

(Note 5)

The ● indicates specifications which apply over the full operating
temperature range; all other limits and typicals TA = 25°C.

Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

Note 2: All voltage values are with respect to ground with DGND and
AGND wired together (unless otherwise noted).

Note 3: When these pin voltages are taken below V

(ground for unipolar

SS

mode) or above VDD, they will be clamped by internal diodes. This product
can handle input currents greater than 60mA below VSS (ground for
unipolar mode) or above VDD without latch-up.

Note 4: When these pin voltages are taken below V

(ground for unipolar

SS

mode), they will be clamped by internal diodes. This product can handle
input currents greater than 60mA below VSS (ground for unipolar mode)
without latch-up. These pins are not clamped to VDD.

Note 5: AVDD = DVDD = VDD = 5V, (VSS = –5V for bipolar mode), f

SAMPLE

400kHz (LTC1278-4), 500kHz (LTC1278-5), tr = tf = 5ns unless otherwise

Note 7: Integral nonlinearity is defined as the deviation of a code from a
straight line passing through the actual endpoints of the transfer curve. The
deviation is measured from the center of the quantization band.

Note 8: Bipolar offset is the offset voltage measured from –1/2LSB when
the output code flickers between 0000 0000 0000 and 1111 1111 1111.

Note 9: Guaranteed by design, not subject to test.
Note 10: Recommended operating conditions.
Note 11: A

must not exceed VDD or fall below VSS by more than 50mV for

IN

specified accuracy. Therefore the minimum supply voltage for the unipolar
mode is 4.95V. The minimum for the bipolar mode is 4.75V, –2.45V.

Note 12: The falling CONVST edge starts a conversion. If CONVST returns
high at a bit decision point during the conversion it can create small errors.
For best performance ensure that CONVST returns high either within 120ns
after conversion start (i.e., before the first bit decision) or after BUSY rises
(i.e., after the last bit test). See mode 1a and 1b (Figures 12 and 13) timing

=

diagrams.

specified.
Note 6: Linearity, offset and full-scale specifications apply for unipolar and

bipolar modes.

W

U

TYPICAL PERFORMANCE CHARACTERISTICS

Integral Nonlinearity vs
Output Code

1.0
f

SAMPLE

0.5

0

INL ERROR (LSB)

–0.5

–1.0

512 1024 1536 2048

0

= 500kHz

2560 3072 3584 4096

CODE

LT1278 G1

Differential Nonlinearity vs
Output Code

1.0
f

= 500kHz

SAMPLE

0.5



0

DNL ERROR (LSB)

–0.5

–1.0

0

512 1024 1536 2048

CODE

ENOBs and S/(N + D) vs
Input Frequency



2560 3072 3584 4096

LT1278 G2

5